1. Field of the Invention
The present invention relates an apparatus for manufacturing a can lid.
2. Description of the Related Art
Can lids are generally manufactured by cutting off a metal sheet into a panel in the shape of a can lid with a press or the like, producing a rivet to fix a tab to the panel, thereafter defining a score in a surface of the panel to produce an opening in the panel, and fixing the tab for opening the panel along the score to the panel with the rivet.
If a can lid is printed with an indicia showing how to use the tab on the panel and also the contents of the can, then the indicia is printed on the metal sheet before it is cut off. Thereafter, the metal sheet is cut off into the panel, after which a rivet is produced, a score is defined, and the tab is fixed. However, since the tab and the indicia are not in a particular controlled positional relationship to each other, the tab often conceals part of the indicia from view.
To avoid the above drawback, some conventional can lids are printed with two identical indicia in respective two areas of the can lid, each occupying a substantially half of the can lid, so that the contents of the can will easily be recognized by the consumer even if part of one of the indicia is concealed from view by the tab. Even if part of one of the indicia is concealed from view by the tab, the other indicia is not concealed from view by the tab, allowing the consumer to recognize the contents of the can.
With a can lid being printed with two identical indicia, however, since each of the indicia is printed in the area that takes up a substantially half of the can lid at maximum. Accordingly, the amount of information represented by each of the indicia is smaller than if an indicia is printed on the can lid except an area covered by the tab. Depending on the position where the tab is attached, the tab and the printed information are superposed on each other, tending to impair the aesthetic appearance of the can lid.
To meet various consumer needs in recent years, there has been a demand for pictures, illustrations, etc. to be printed on can lids. However, if tabs are attached in various different positions to can lids with such printed pictures or illustrations, then the aesthetic appearance of the can lids is also reduced.
In view of consumer""s daily demands for food and beverage can lids that can be opened more easily, there have been proposed various can lids with improved opening score and tab shapes for easier can openability.
However, even can lids with identical score and tap shapes can be opened by the user under widely different opening forces. Some can lids need to be opened under much greater opening forces than other can lids. When such can lids that can be opened under widely different opening forces are used on canned products, they do not meet consumer""s needs for easily openable canned products.
The inventors have found that the positional relationship between the rolling direction of the panel of a can lid and a score and a tab greatly affect an opening force required to open the panel. A sheet from which the panel of a can lid is manufactured has been rolled in a certain rolling direction and cut to a predetermined length. After a disk-shaped panel is blanked out of the sheet, the direction of the blanked panel is not controlled. Therefore, in a subsequent process, the rolling direction and the tab direction in which the tab is fixed to the panel are not in a fixed relationship to each other. After a rivet is produced and a score is defined in the panel, a tab is fixed to the panel. When the tab is fixed to the panel, since the tab direction in which the tab is attached and the rolling direction of the panel are not in a constant relationship to each other, can lids thus manufactured need various opening forces to open the panels.
It is an object of the present invention to provide an improved apparatus for manufacturing a can lid.
Another object of the present invention is to provide an apparatus for manufacturing a can lid with a tab attached in a position matching a property of a panel of the can lid.
To achieve the above objects, there is provided in accordance with a first aspect of the present invention an improvement in an apparatus for manufacturing a can lid, comprising feed means for feeding a panel to be processed into a can lid, rivet producing means for producing a rivet on the panel fed by the feed means, score notching means for notching a score for opening the panel therealong in the panel which is fed by the feed means and on which the rivet is produced by the rivet producing means, and tab attaching means for securing a tab to the panel which is fed by the feed means and in which the score is notched by the score notching means, with the rivet.
The apparatus also includes detecting means disposed upstream of the rivet producing means, for detecting an indicia representing a tab direction in which the tab is attached, on the panel fed by the feed means, angle calculating means for calculating an angle through which to turn the panel in order to align the tab direction represented by the indicia with a reference direction extending between the center of the panel and a position in which the rivet is produced by the rivet producing means, and turning means for turning the panel through the angle calculated by the angle calculating means.
With the above arrangement, the detecting means detects the indicia representing the tab direction in which the tab is attached, on the panel, and the angle calculating means and the turning means bring the tab direction represented by the indicia into alignment with the reference direction extending between the center of the panel and the position in which the rivet is produced by the rivet producing means. The rivet producing means produces a rivet on the panel with the tab direction aligned with the reference direction, the score notching means notches the score in the panel, and the tab attaching means secures the tab with the rivet. The apparatus according to the present invention can manufacture can lids with tabs secured at a constant position to panels, and hence can manufacture can lids where tabs are attached at a position matching a property of the panels.
If the panel is printed on a surface thereof with a second indicia off a position in which the tab is attached, then the detecting means comprises means for detecting the second indicia, the angle calculating means comprises means for calculating an angle through which to turn the panel in order to align the tab direction represented by the second indicia with the reference direction, and the turning means comprises means for turning the panel through the angle calculated by the angle calculating means, whereby the second indicia is not covered with the tab.
If an instruction remark explanatory of how to use the tab is printed as the second indicia, then since the printed instruction remark is not covered with the tab, the consumer can easily recognize the instruction remark. Since the same indicia is not required to be printed in two locations unlike the conventional practice, a greater amount of information can be printed on the panel than heretofore. Because the second indicia is not covered with the tab, the manufactured can lid has an aesthetic appearance.
Preferably, the detecting means comprises image recognizing means for recognizing the surface of the panel with an image, and the angle calculating means comprises means for dividing the surface of the panel into a normal area which extends up to 180xc2x0 clockwise from the reference direction and a reverse area which extends less than 180xc2x0 counterclockwise from the reference direction, calculating an angle clockwise from the reference direction to the indicia if the detected indicia is in the normal area, and calculating an angle counterclockwise from the reference direction to the indicia if the detected indicia is in the reverse area.
The angle calculating means divides an image of the panel recognized by the image recognizing means into the normal area which extends up to 180xc2x0 clockwise from the reference direction and the reverse area which extends less than 180xc2x0 counterclockwise from the reference direction. The angle calculating means calculates an angle clockwise from the reference direction to the indicia if the detected indicia is in the normal area, and calculates an angle counterclockwise from the reference direction to the indicia if the detected indicia is in the reverse area. Therefore, the angle calculated by the angle calculating means does not exceeds 180xc2x0, and the angle through which the panel is turned by the turning means does not exceeds 180xc2x0. Consequently, the indicia can quickly be turned to the reference direction.
In the apparatus according to the first aspect of the present invention, if the indicia representing the tab direction comprises a pattern applied to the panel, the detecting means preferably comprises illuminating means for irradiating the panel with light, light-detecting means for detecting light from the irradiated panel, second turning means for turning one or both of the panel and the light-detecting means, and pattern recognizing means for recognizing the pattern based on a signal produced by the light-detecting means when the light-detecting means detects the reflected light from the panel in a circumferential direction thereof. The angle calculating means comprises means for comparing a normal position pattern for the pattern in a position where the tab direction represented by the pattern is aligned with the reference direction, with the pattern recognized by the pattern recognizing means, and calculating an angle through which to turn the panel in order to align the recognized pattern with the normal position pattern, and the turning means comprises means for turning the panel by the calculated angle.
The pattern applied to the panel is effective in recognizing the tab direction. The second turning means turns one or both of the panel or the light-detecting means, and the light-detecting means detects the reflected light in the circumferential direction from the panel irradiated by the illuminating means. The pattern recognizing means receives the signal from the light-detecting means and recognizes the pattern applied to the panel based on the received signal. The recognized pattern allows the tab direction on the panel to be recognized. The angle calculating means calculates an angular deviation between the recognized pattern and the normal position pattern, and the turning means brings the tab direction on the panel into alignment with the reference direction.
If the pattern is a printed pattern on the panel, then the tab can be secured to the panel at a given position on the printed pattern, the pattern can be designed in view of the position of the tab, so that can lid can be manufactured which satisfies various needs of the consumers and have an aesthetic appearance.
Preferably, the light-detecting means comprises a plurality of sensors disposed at angular intervals in the circumferential direction of the panel, for detecting the reflected light from the panel while one or both of the panel or the light-detecting means are turned through a predetermined angle by the turning means, and the pattern recognizing means comprises means for combining signals from the sensors to recognize the pattern. The sensors disposed at angular intervals in the circumferential direction of the panel are capable of detecting the reflected light from the panel fully in the circumferential direction when one or both of the panel and the light-detecting means are turned through a predetermined angle. Consequently, the reflected light from the panel in the circumferential direction can be detected by the light-detecting means in a short period of time.
In order for the angle calculated by the angle calculating means not to exceed 180xc2x0, the angle calculating means preferably comprises means for calculating the angle clockwise if the angle through which to turn the panel to align the recognized pattern with the normal position pattern is up to 180xc2x0, and calculating the angle counterclockwise if the angle through which to turn the panel to align the recognized pattern with the normal position pattern is less than 180xc2x0.
According to a second aspect of the present invention, there is provided an apparatus for manufacturing a can lid, comprising, in addition to the feed means, the rivet producing means, the score notching means, and the tab attaching means, detecting means for detecting an indicia representing the rolling direction on the panel fed by the feed means, angle calculating means for calculating an angle through which to turn the panel in order that the rolling direction represented by the indicia and a reference direction extending between the center of the panel and a position in which the rivet is produced by the rivet producing means extend at an angle ranging from 0xc2x0 to 45xc2x0, and turning means for turning the panel through the angle calculated by the angle calculating means, the score notching means comprising means for notching the score such that a portion of the score along which the tip end of the tab tears off the panel extends at an angle ranging from 45xc2x0 to 90xc2x0 to the rolling direction.
The inventors have found that the force required to open the panel along the score is minimum if the portion of the score along which the tip end of the tab tears off the panel extends perpendicularly to the rolling direction, and that the force required to open the panel along the score is small if the angle from the portion of the score to the rolling direction is 45xc2x0 clockwise or 45xc2x0 counterclockwise. In the apparatus according to the second aspect of the invention, the angle calculating means calculates the angle through which to turn the panel in order that the rolling direction and the reference direction extend at an angle ranging from 0xc2x0 to 45xc2x0 to each other, and the score notching means notches the score such that the portion of the score along which the tip end of the tab tears off the panel extends at an angle ranging from 45xc2x0 to 90xc2x0 to the rolling direction. Therefore, the can lid can be opened under a small opening force whose variations are small.
Preferably, the angle calculating means comprises means for calculating an angle through which to turn the panel in order to align the rolling direction with the reference direction, so that the portion of the score along which the tip end of the tab tears off the panel extends perpendicularly to the rolling direction, minimizing the opening force required to open the panel along the score.
In the apparatus according to the second aspect of the present invention, the angle calculating means preferably comprises means for calculating the angle clockwise if the angle through which to turn the panel in order that the rolling direction and the reference direction extend at an angle ranging from 0xc2x0 to 45xc2x0 is up to 180xc2x0, and calculating the angle counterclockwise if the angle through which to turn the panel in order that the rolling direction and the reference direction extend at an angle ranging from 0xc2x0 to 45xc2x0 is less than 180xc2x0. With this arrangement, the angle calculated by the angle calculating means does not exceeds 180xc2x0, and the angle through which the panel is turned by the turning means does not exceeds 180xc2x0. Consequently, the indicia can quickly be turned to the reference direction.
In the apparatus according to the second aspect of the present invention, if the indicia comprises a striped pattern produced when the metal sheet is rolled, then the detecting means preferably comprises illuminating means for irradiating the panel with light, light-detecting means for detecting light from the irradiated panel, second turning means for turning one or both of the panel and the light-detecting means, and pattern recognizing means for recognizing the striped pattern based on a signal produced by the light-detecting means when the light-detecting means detects the reflected light from the panel in a circumferential direction thereof. The angle calculating means comprises means for comparing a normal position pattern for the striped pattern in a position where the rolling direction represented by the striped pattern is aligned with the reference direction, with the striped pattern recognized by the pattern recognizing means, and calculating an angle through which to turn the panel in order to allow the recognized pattern with the normal position pattern to extent at an angle ranging from 0xc2x0 to 45xc2x0 to each other, and the turning means comprises means for turning the panel by the calculated angle.
The panel bears the striped pattern on its surface which is produced when the material of the panel is rolled. When the striped pattern is recognized to detect the rolling direction of the material of the panel, the score can be notched such that the portion of the score along which the tip end of the tab tears off the panel extends at an angle ranging from 45xc2x0 to 90xc2x0 to the rolling direction. The can lid thus manufactured can be opened under a small opening force whose variations are small.
In order to minimize the opening force, the angle calculating means preferably comprises means for calculating an angle through which to turn the panel in order to align the recognized pattern with the normal position pattern.
As with the first aspect of the present invention, the light-detecting means preferably comprises a plurality of sensors disposed at angular intervals in the circumferential direction of the panel, for detecting the reflected light from the panel while one or both of the panel or the light-detecting means are turned through a predetermined angle by the turning means, and the pattern recognizing means preferably comprises means for combining signals from the sensors to recognize the striped pattern.
Preferably, if the angle calculating means comprises means for calculating the angle clockwise if the angle through which to turn the panel in order that the recognized pattern and the normal position pattern lie at an angle ranging from 0xc2x0 to 45xc2x0 to each other is up to 180xc2x0, and calculating the angle counterclockwise if the angle through which to turn the panel in order in order that the recognized pattern and the normal position pattern lie at an angle ranging from 0xc2x0 to 45xc2x0 to each other is less than 180xc2x0.
The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.